Mixtures of tetramethyldisiloxane or hexamethyldisiloxane, octamethylcyclotetrasiloxane, and hexamethylcyclotetrasiloxane can be converted into both terminal and side chain hydrogenpolysiloxanes or side chain hydrogenpolysiloxanes through acid equilibration. These hydrogenpolysiloxanes react with various alkenes in the presence of platinum catalysts to provide corresponding addition products. However, hydrogenpolysiloxanes having (meth)acryl side chains and terminated with hydrogen at each end are not known in the art. In addition, although methyl side chain hydrogenpolysiloxanes can be readily converted to addition products through addition reaction of allyl (meth)acrylate to some Si--H bonds thereof, no reports have been found with respect to methylphenyl-containing hydrogenpolysiloxanes. This is because phenyl-containing siloxanes are equilibrated with alkali catalysts and thus reject the use of Si--H compounds.
In the prior art, .alpha.-methylstyrene was generally used in order to incorporate an aromatic substituent into hydrogenpolysiloxanes, but the resulting siloxanes are less resistant against weather and not recommended for use where they are exposed to ultraviolet light and sunlight. Unless an aromatic substituent is introduced, polysiloxanes remain low in compatibility and reactivity with organic resins. Therefore, there is a need for a reactive polysiloxane containing a proper content of phenyl group as a modifier for organic resins.
From the past, organopolysiloxanes having an organic functional group were widely used as resin modifiers in the fields of paint, molding materials, medical materials, and coating materials for the purpose of imparting useful properties such as heat resistance, weather resistance, mold release, formability and thermal impart to organic resins.
There were known various organopolysiloxanes having an organic functional group, for example, dimethylpolysiloxane having an alcoholic hydroxyl group at either end (see Japanese Patent Publication No. 8718/1979), dimethylpolysiloxane having a functional group at either end (see Japanese Patent Application Kokai Nos. 217515/1983 and 123502/1984), methylpolysiloxane having a functional group on a side chain (see Japanese Patent Publication Nos. 18968/1986 and 288808/1986), and methylphenylpolysiloxane having an alcoholic hydroxyl group at either end and on a side chain. All these organopolysiloxanes have the same functional groups in their molecule and no polysiloxanes having different functional groups in a molecule have been proposed. The organopolysiloxanes having the same functional groups in their molecule possess properties corresponding to the respective functional groups.
There is a need for an organopolysiloxane which is more compatible with organic resins and more effective as a resin modifier than the conventional organopolysiloxanes.